The American Diabetes Association estimates that there are currently 5 million people in the United States with confirmed diabetes, and over 10 million at risk. Care of diabetics consumes a total of $98 billion per year, accounting for one of every seven healthcare dollars spent in the U.S. There are 24,000 new cases of diabetes-caused blindness caused by diabetes each year. Diabetes is the leading cause of kidney failure, contributing about 40% of new dialysis patients. Diabetes is also the most frequent cause of lower limb amputation, with 56,000 limbs lost to diabetes each year. Type I diabetes mellitus (also known as insulin-dependent diabetes) is a severe condition accounting for 5-10% all diabetics.
There are several clinical tests underway to transplant diabetics with islet cells isolated from donor pancreas. This has been made possible by recent advances in the isolation and transplantation of islet cells. For example, the Edmonton Protocol was developed in the 1990's, and over 200 people have received cadaveric islet transplants using that protocol.
However, the supply of islet cells from cadaveric donors limits the application of islet transplants as a large-scale therapy. Thus, the development of methods for differentiating and purifying islet cells from a renewable source such as embryonic stem cells is an important goal. For embryonic stem cell derived islet cells to become a commercially viable proposition, there is a need to develop new procedures that provide for populations of islet cells of high purity.